The primary objective of this research program is to gain understanding of central integrative mechanisms in cortical regions of the mammalian brain. The specific region to be analyzed is the olfactory bulb; because of its simple structure and separated pathways it offers the possibility for rigorous physiological analysis with relatively unambiguous results. Physiological experiments employing single volleys and microelectrode recordings are aimed at testing and extending the biophysical neuron models developed for mitral and granule cells. Further evidence will be sought for functional properties of dendrodendritic synaptic pathways in the bulb. Anatomical studies will be designed to elucidate the organization of the input and output pathways of the bulb. Analysis of unitary responses will be carried out with the aim of establishing the neuronal basis of olfactory discrimination. This will require continued development of highly controlled olfactory apparatus. A complementary research program is concerned with analysis of response mechanisms in the isolated frog muscle spindle. Further evidence will be sought for properties of mechanoelectric transduction and the effort will be made to develop new and quantitative models for the muscle spindle response.